1. Field of the Invention
The invention relates generally to cooking apparatus and systems having heaters and capable of air purge.
2. Description of Related Art
When preparing food in fryer apparatus that use cooking media, including, for example, an open fryer and a pressure fryer, the quality of the cooking medium (e.g., an oil, a liquid shortening, a meltable-solid shortening, and a semi-solid shortening) may impact the quality of the food products (e.g., poultry, fish, and potato products) that are cooked. Known fryer apparatus may include one or more cooking chambers, e.g., fryer pots or vats, which may be filled with a cooking medium.
As the cooking medium is used to cook food, particles of food may contaminate the cooking medium. The flavor characteristics of each of these food particles may become infused in the cooking medium. This infusion may affect food quality adversely. Moreover, upon heating the cooking medium, the cooking medium may undergo chemical reactions e.g., hydrolysis, oxidation, or polymerization, or combinations thereof. These chemical reactions may result in compounds, such as free fatty acids, hydroperoxides, or polymerized triglycerides, or combinations thereof. In addition, such reactions may reduce the viscosity of the cooking medium, which also may adversely affect cooking performance. Thus, a filtering process is often implemented to drain the cooking medium from the cooking chamber into a filter vessel, filter the medium, and return the filtered medium to the cooking chamber. After a time, the cooking medium needs to be replaced. The cooking medium in use ranges from low viscosity liquid to essentially solid at room temperature. The new cooking medium is packaged in containers, e.g., metal or plastic containers or the like, to be used in the cooking apparatus. In addition, cooking media within lines or pipes in the cooking apparatus solidify due to local freezing or hardening.